Ti 4+ to Ti 3+ Conversion of TiO 2 Uppermost Layer by Low-Temperature Vacuum Annealing: Interest for Titanium Biomedical Applications

Abstract

Because of the Ti 3+ defects responsibility for dissociative adsorption of water onto TiO 2 surfaces and due to the hydroxyls influence on the biological behavior of titanium, controlling the Ti 3+ surface defects density by means of low-temperature vacuum annealing is proposed to improve the bone/implant interactions. Experiments have been carried out on Ti-6Al-4V alloys exhibiting a porous surface generated primarily by chemical treatment. XPS investigations have shown that low-temperature vacuum annealing can create a controlled number of Ti 3+ defects (up to 21% Ti 3+/Ti 4+ at 573 K). High Ti 3+ defect concentration is linked to surface porosity. Such surfaces, exhibiting high hydrophilicity and microporosity, would confer to titanium biomaterials a great ability to interact with surrounding proteins and cells and hence would favor the bone anchorage of as-treated implants.